Conventional pharmaceutical preparations for percutaneous administration of a drug for the treatment or prevention of topical or systemic diseases include adhesive-backed tapes or sheetings comprising a support having provided thereon an adhesive layer containing an active ingredient such as methyl salicylate, menthol, etc.
In these dermal preparations, acrylic pressure-sensitive adhesives have been employed from the standpoint of adhesion to the skin, internal cohesiveness, and stability of the drug to decomposition with time.
Considering diffusion and delivery of a drug to the skin in percutaneous administration, it is desirable that the drug should be in a dissolved state in the pressure-sensitive adhesive. However, since many of the acrylic pressure-sensitive adhesives generally have poor hydrophilic properties, when a hydrophilic drug is incorporated into such an adhesive in an amount enough to produce significant pharmacological effects, the drug is liable to crystallize in the adhesive layer to cause problems of adhesion, diffusion, and liberation of the drug into the body.